Molding apparatus having mandrel with eccentric portion



Feb.4, 195 8 J. A.ILASATER 2,821,755

MOLDING APPARATUS HAVING MANDREL WITH ECCENTRIC PORTION "iFiled' Nov. 1,1955 2 Shets-Sheet 1 FIG INVENTOR. JOHN A. LASATER Feb. 4, 1958 J.A.'L.=A-SATER 2,821,755.

MOLDING APPARATUS HAVING MANDREL WITH ECCENTRIC PORTION Filed Nov. l,-1955 2'Sheets-Sheet 2 INVENTOR. JOHN A LASATER United States Patent@MOLDING APPARATUS HAVING MANDREL WITH ECCENTRIC PORTION John A. Lasater,Chattanooga, Tenn., assignor to Herman Pneumatic Machine Company,Pittsburgh, Pa, a corporation of Pennsylvania Application November 1,1955, Serial No. 544,219

3 Claims. (Cl. 22-22) This invention relates to molding apparatus havinga mandrel with an eccentric portion. It is concerned primarily with theformation of an elongated generally cylindrical mold of small diameterof compacted mold forming material such as may be employed in thecasting of elongated articles such, for example, as elongated hollowarticles such as lengths of pipe.

United States Patent No. 2,449,900 discloses apparatus for forming moldsfor centrifugal casting and centrifugally casting products therein. Thepresent invention is applicable to the apparatus of said patent. Anotherform of apparatus adapted for modification in accordance with thepresent invention is disclosed in copending United States applicationSerial No. 427,842, filed May 5, 1954.

The patent and application above referred to disclose apparatusincluding a rotary hollow flask in which mold forming material may becompacted to form a mold whereafter the flask with the mold of compactedmold forming material therein is employed for the centrifugal casting ofelongated hollow objects. The present improvement in the art isconcerned particularly with the forming of the elongated hollow mold.After the mold is formed in accordance with my invention the elongatedhollow ob ject may be cast as disclosed in said patent and application.Indeed, while I contemplate forming a mold of compacted mold formingmaterial while rotating the flask at centrifugal speed, the mold which Iform has utility otherwise than in the centrifugal casting field; it maybe employed in non-centrifugal casting.

The patent and application above referred to disclose the introductioninto a flask of finely divided mold forming material such as sand,graphite, a mixture of sand and graphite or other similar mold formingmaterial, the initial spreading of the mold forming material about theinterior of the flask through rotation of the flask at cenl flask whilethe flask rotates and the compacting of the mold forming material in theflask by the action of the mandrel. The mandrel is mounted for rotationbut is not driven in its rotative movement. It turns through contactwith the mold forming material. The mandrel is of smaller diameter thanthe mold being formed so the mandrel in effect rolls generally along theinside of the flask during mold formation While the flask is rotated atcentrifugal speed. The mandrel is mounted in cantilever fashion in abearing mounted in a carriage and the carriage may be advanced toproject the mandrel into and through the flask, a complementary bearingbeing provided at the opposite end of the flask so that when the mandrelhas been projected through the flask it is mounted in bearings adjacentboth ends of the flask and is free to rotate. The relative transversemovement between the mandrel and the flask may be effected bymovingeither the mandrel or the flask or both. In the above mentioned patentthe mandrel is moved while in the above mentioned application the flaskis moved. The patent and application disclose machines in which aplurality or battery of flasks are employed side by side. The presentiiinvintion is applicable to a machine having one or more as s.

The apparatus disclosed in the patent and application above mentioned issuitable for forming pipe such as soil pipe of three-inch and four-inchsize. If that apparatus is attempted to be utilized for forming pipe ofsmaller size such, for example, as two-inch soil pipe, a Very slendermandrel has to be used, the mandrel being so slender that if it werepressed continuously against the mold forming material in the flaskduring compacting of the mold forming material the mandrel would bendinwardly so that the mold formed thereby would be of undesirably reduceddiameter at the center. When it is desired to form a mold which iscylindrical and of uniform diameter the bending or deflection of aslender cylindrical mandrel will result in the formation of a mold whichis somewhat necked in at the center. To overcome the above explaineddifliculty in the making of molds for casting small diameter pipe andother elongated hollow objects the so-called bellied mandrel of UnitedStates Patent No. 2,499,387 was developed. The theory of the belliedmandrel is to compensate for deflection of the mandrel so that when themandrel 1s deflected it will form a straight mold. However, with thebellied mandrel there may be some difficulty in obtaining uniformaccuracy in mold size and shape.

I provide molding apparatus in which a slender mandrel may be employedfor forming a mold for the casting of small diameter pipe, the mandrelbeing so slender that if it were pressed continuously against the moldforming material in the flask during compacting of the mold formingmaterial the mandrel would bend inwardly so that the mold formed therebywould be of undesirably reduced diameter at the center. I form themandrel with an eccentric portion which strikes the mold form-ingmaterial with successive blows as the mandrel and flask rotate and themandrel moves relatively to the flask away from the axis of the flask.Due to the fact that the mandrel is not pressed continuously against themold forming material in the flask during compacting of the mold formingmaterial the tendency to bend the slender mandrel is obviated. While atthe moments when the mandrel is in contact with the mold formingmaterial there may be a slight tendency to bend the mandrel thattendency is immediately overcome by the mandrel parting contact with themold forming material. As the flask rotates the eccentric portion of themandrel subjects the mold forming material in the flask to a successionof blows at circumferentially spaced apart portions of the flask. Themold forming material in the flask is intermittently engagedsuccessively at circumferentially spaced apart zones extendinglengthwise of the flask and thereby compacted against the flask. Theintermittent engagement of the mold form-ing material in the flask bythe mandrel is continued until a substantially circular uniformlycompacted mold has been formed. Preferably during rotation of the flaskwith mold forming material therein at centrifugal speed the mold formingmaterial is intermittently rolled in the flask successively atcircumferentially spaced apart zones extending lengthwise of the flaskwhereby the mold forming material is compacted against the flask.

In referring to circumferentially spaced apart zones of the mold formingmaterial with which the eccentric mandrel comes into engagement 1 do notnecessarily mean that each such zone of engagement is separated from thezones at either side of it by a space; I simply mean that the zonesprogress circumferentially of the flask. Theymay overlap one another andindeed such overlapping is conducive to efliciency and efiective mold 3.formation. It is found that as the flask rotates the zones of engagementof the mandrel with the mold forming material creep along the flaskcircumferentially so that the result in the end'is a smooth-cylindricalmold rather than a fluted mold such as might be formed if the mandrelengaged the mold forming material at precisely the same places upon eachrevolution of the flask. The flask and mandrel are not geared together,the rotation of the mandrel being derived entirely from its contact withthe mold forming material. There is, of course. some slippage and nospecial precaution need be taken to guard against tracking of themandrel with the mold forrning material and consequent formation of afluted mold.

Preferably the rotary hollow flaskhas an enlargement at an end thereofand the mandrel has an enlargement at an end thereof generally radiallyaligned with the enlargement in the flask, the enlargement in themandrel being coaxial with the axis of rotation of the mandrel, themandrel having an eccentric portion which strikes the mold formingmaterial with successive blows as-the mandrel and flask rotate and themandrel moves relatively to the flask away from the axis of the flask.For the formation of so-called double hub pipe the mandrel and flaskhave such enlargements at both ends.

In a preferred form of molding apparatus a rotary hollow flask isprovided together with bearing means for supporting for rotation amandrel extending within the flask and adapted to rotate therein as theflask rotates to compact mold forming material against the inside of theflask, means for relatively moving the flask and bearing meanstransversely of the axes thereof and a mandrel having a portion ofcircular cross section disposed in the bearing means so that the axis ofsaid portion of. the mandrel is the axis about which the mandrel rotatesin the bearing means, the mandrel having within the flask a portionwhich is eccentric to the axis of rotation of the mandrel, the eccentricportion of the mandrel striking the mold forming material in the flaskwith successive blows as the mandrel and flask rotate and the mandrelmoves relatively to the flask away from the axis of the flask. Desirablybearing means are provided at both ends of the flask forrotatablysupporting the mandrel as above mentioned.

Other details, objects and advantages of the invention will becomeapparent as the following description of cer-- tain present preferredembodiments thereof proceeds.

In the accompanying drawings I have shown certain present preferredembodiments of the invention in which:

Figure l is a side view, partly in cross section and with parts brokenaway, of a mandrel having an eccentric portion, a member forming anenlargement applicable to the mandrel for forming the portion of themold for casting of a pipe hub or bell being shown in chain lines;

Figure 2 is a transverse cross-sectional view to enlarged scale taken onthe line 1III of Figure 1;

Figure 3 is a fragmentary detail view showing the support for theforward end of the mandrel in operative mandrel-supporting position; and

Figure 4 is a view similar to Figure 3 showing the support for theforward end of a mandrel provided with a member cooperating with themandrel for forming in the mold at the end thereof shown in the figure aportion for casting one of the hubs of double hub pipe, the support forthe forward end of the mandrel and said member being in operativeposition.

Referring now more particularly to the drawings, the centrifugal castingapparatus is of the type disclosed in the above mentioned patent andapplication and-comprises a rotatable flask with, of course, means forrotating theflask and a freely rotatable mandrel mounted in cantileverfashion for movement into the flask with a bearing for the forward endof the shaft when it is disposed within the flask andmeans forrelatively adjusting at' will the distancebetween the axis of the flaskand the axis of the mandrel.

I show in Figure 3 a flask 16 for the casting of single hub soil pipeand in Figure 4 a flask 16a for the casting of double hub soil pipe, itbeing understood that in each case a hub is cast in the pipe at theright hand end of the flask which is not shown in the drawings.Elongated articles other than lengths of pipe may be centrifugally castand materials other than iron may be employed. For example, other metalsor non-metallic materials of suitable structural characteristics may beutilized.

To avoid complexity of the drawings I havenot shown in detail thestructure for rotatably mounting the flasks. Such structure is now amatter of knowledge to those skilled in the art. The flasks, may, forexample, be mounted for rotation as shown in United States Patent No.2,449,900.

Means are provided for rotating the flasks 16 at centrifugal speed so asto form therein centrifugally cast hollow elongated articles. Such meansare'so well known that they are not shown. A mandrel 25 is shown inFigure 3 for casting single'hub pipe and a mandrel 20 is shown in Figure4 for casting double hub pipe. The

mandrels are mounted to'be rotated by frictional engagement with thefinely divided mold formingmaterial used for forming molds in the flasksas will presently be described. The mandrels partake of only twomotions, the rotative motion just mentioned and axial movement into andout of the flasks. The mandrels 20 and 25 are respectively coaxial withthe flasks 16a and 16 when the mandrels are moved into and out of'theflasks. When the mandrels are in coaxial relationship with the flasksand finely divided mold forming material has beenintroduced into theflasks and the flasks are rotated themandrels are introduced into theflasks.

Referring now more in detail to the structure and operation of themandrels 20 and 25, as stated above the mandrel 25 is shown in Figures 1and 2. At its righthand end it is provided with a cylindrical bearingportion 25a adapted to be mounted in suitable bearings in a mandrelsupport so that the mandrel is freely rotatable about its axis. To theleft of the bearing portion 25a viewing Figure l the mandrel 25 has anenlargement 25b and projecting to the left therefrom a cylindricalportion 250. A member 25d, shown in chain lines,.for forming in the molda portion for casting of a pipe hub or bell is applied to the mandreland fastened in place by bolts 25c. All of the parts of the mandrel thusfar described, to Wit, parts 25a, 25b, 25c and 25d, .are of circularcross section and coaxial.

Coaxial with the mandrel portions 25a, 25b, 25c and 25d is an annularoutward projection 66 for the purpose of forming in the mold adepression for casting of the spigot at the end of a length of singlehub pipe opposite the end at which the hub or bell of the pipe isdisposed. To the left of the projection 66 and coaxial therewith are areduced portion 67 and a bearing portion 61 adapted to enter a hearingas will presently be described to rotatably support the end of themandrel remote from the end having the bearing portion 25a. All of theportions 25a, 25b, 25c, 25d, 66, 67 and 61 are of circular cross sectionand coaxial.

Intermediate the portions 250 and 25d to the right, and the portion 66to the left, viewing Figure l, the mandrel has a portion 251 which isnon-coaxial or eccentric with respect to the portions above mentioned.The portion 25 is shown as of circular cross section but may be of othercross section since normally only the part thereof farthest from theaxis of rotation of the mandrel is operative in forming a mold, thatbeing the part shown at the top in Figures 1 and 2. The same structureis shown in Figure 3 but in that figure the mandrel has been rotatedfrom the position shown in Figures 1 and 2. Thus when the mandrel turnsit turns about the common axis of the parts 25a, 25b, 25c, 25d, 66, 67and '61 and the part 25) partakes of eccentric rotation, i. e., turnsabout an axis offset from its own axis as is characteristic of eccentricmovement.

I have shown the mandrel parts 66, 67 and61 as though they were formedintegrally with the remaining parts of the mandrel although if desiredthey may be formed separately and applied to the remainder of themandrel as shown in the above mentioned copending application. Since thefeature to which attention is being primarily directed in the presentapplication is the eccentricity of the portion 25 of the mandrel andsince the detailed structure of the bearing portion of the mandrel maybe varied so longas provision is made for supporting of the mandrel torotate about the common axis of the parts 25a, 25b, 25c, 25d, 66, 67 and61 I have not attempted to show or describe in detail the bearingportion of the mandrel.

The mandrel 20 is identical with the mandrel 25 except that instead ofhaving a spigot forming projection 66 the mandrel 2d has a cylindricalportion 86 to which a member 84 to be referred to further below may beapplied for forming in the mold a portion for the casting of a hub whendouble hub pipe is to be made. The member 84 may be applied from theleft-hand end of the mandrel 2% viewing Figure 4. The mandrel 20 has abearing portion 61a which may be identical with the bearing portion 61of the mandrel 25. The portions of the mandrel 29 corresponding with theportions 25a, 25b, 25c and 25d of the mandrel 25" and the portions 86,84 and 61a of the mandrel 20 are all coaxial. The mandrel 20 has aneccentric portion 25g which may be identical with the eccentric portion2d of mandrel 25.

As above indicated the apparatus is adaptable for forming either singlehub or double hub pipe, Figure 3 showing apparatus for forming a moldfor the casting of single hub pipe and Figure 4 showing apparatus forforming a mold for the casting of double hub pipe. When single hub pipeis to be cast the hub is formed at the right-hand end of each flaskviewing Figures 3 and 4, the spigot being formed at the lefthand end,which is the end shown in Figure 3. Each of Figures 3 and 4 showsmechanism cooperating with one flask; it is to be understood that themandrel support shown in those figures as well as the core holder shownin Figure 4 when double hub pipe is to be formed are duplicated for eachflask.

i provide a carrier 77 having means for supporting the forward end ofthe mandrel 20 or 25 positioned in alignment with the mandrel. The bodyof the carrier 77 is of generally hollow shape as shown in Figures 3 and4. The wall of the carrier which is disposed toward the right viewingFigures 3 and 4 has a circular opening 78 therein, such opening beingsubstantially coaxial with the flask 16 or 16a. Applied to the carrier77 at the opening 78 is a bearing bracket 79. The bearing bracket 79 isfalstened to the carrier 77 by any suitable fastening means, not shown,and which may, for example, be as disclosed in copending applicationSerial No. 285,213, filed April 30, 1952. Disposed within the bearingbracket 79 is a bearing unit 86 of any suitable type, such, for example,as a Dodge bearing unit. The bearing unit 80 may be maintained withinthe bearing bracket 79 by being pressed therein. The bearing unit 80 hasa generally cylindrical opening therethrough as known to those skilledin the art for receiving a rotatable machine part.

i provide for rotatably mounting in the bearing unit 80 a part whoseform is determined by whether the pipe being cast is single hub pipe ordouble hub pipe. For casting single hub pipe that part is in the form ofa flanged sleeve 81 shown in Figure 3 serving as a pilot or mandrelsupport. The flange of the pilot is designated 82 and serves as a guardto prevent mold forming material from getting into the bearing unit. Thebore of the pilot is dimensioned to snugly and guidingly receive themandrel portion 61 as shown in- Figure 3. The pilot supports the end ofthe mandrel while the mandrel is performing its mold forming function.

When double hub pipe is to be cast the pilot 81 is replaced by acombination pilot and hub 83 as shown in Figure 4. The combination pilotand hub 83 may be formed in one piece as shown or in two pieces boltedor otherwise fastened together. The hub portion is the member 84 andprojects axially from the pilot portion as shown in Figure 4. The hub 84is adapted to be engaged by the portion 36 of the mandrel when themandrel is introduced into the flask, the hub lying within the flask toform an enlargement at the end of a mold of compacted mold formingmaterial in the flask to form one of the hubs or bells on the pipe beingcast. The nose of the hub 84 is tapered as shown at 85 and has a bore86a of such size as to snugly receive the portion 86 of the mandrel 20.The rearward portion of the hub 84 is hollowed out and has passages 87to permit mold forming material pushed into the hub by the end of themandrel to be discharged centrifugally upon rotation of the mandrel andhub.

The axial distance from the end of the mandrel to the tapered shoulderbetween the portions 61a and 86 is greater than the axial distancebetween the extremity of the hub 84 and the mouth of the pilot. This isto insure that the mandrel will be in guided relationship to the pilotwhen the portion 86 of the mandrel 20 enters the bore 86a of the hub 84whereby to avoid damage to the hub.

I shall now describe a present preferred method of casting single hubpipe by use of my apparatus. At the end of a cycle the flask is ingenerally upright position and is open top and bottom since the pipecast during that cycle has been discharged downwardly therefrom. Themold and core or cores have likewise been so discharged. The first stepis to close the lower end of the flask. When the lower end of the flaskhas been closed finely divided mold forming material is introduceddownwardly into the flask. The flask may be used to measure the quantityof finely divided mold forming material introduced as disclosed inPatent No. 2,598,554. As soon as the finely divided mold formingmaterial has been introduced into the flask rotation of the flask iscommenced and at the same time the flask is turned to a position inwhich its axis is substantially horizontal. The rotation of the flaskcentrifuges the mold forming material so that an opening is formed inthe mold forming material extending generally axially of the flask.About the time the flask reaches horizontal position the end of theflask which was originally the lower end (the right hand end viewingFigures 3 and 4) is opened. The mandrel 25 is moved from right to leftviewing Figures 1 and 3 to introduce the mandrel into the flask throughthe opening in the finely divided mold forming material formed by theinitial centrifuging of the mold forming material above described and todispose the mandrel portion 61 in the pilot 81.

When the mandrel is supported in coaxial relationship with the flask (i.e., with the portion of the mandrel except the eccentric portion 25thereof in coaxial relationship with the flask) with the leading end ofthe mandrel disposed in the pilot 81 as shown in Figure 3, and whilerotation of the flask continues, the flask is moved transversely of itsaxis as disclosed in said copending application Serial No. 427,842whereby the mandrel consolidates and smooths the mold forming materialin the flask. The portion 25d of the mandrel forms in the mold theportion for casting of the pipe hub or bell and the portion 66 forms theportion of the mold for casting of the spigot. The portions 25d and 66are concentric with the axis of rotation of the mandrel and engagementthereof with the mold forming material causes turning of the mandrel asthe flask rotates and the mandrel is pressed against the mold formingmaterial. As the eccentric portion 25] of the mandrel turns about themandrel axis it strikes the mold forming material with repeated blowsand thereby consolidates and smooths the mold forming material withoutsubstantial bending or deflection of the mandrel despite the fact thatthe mandrel is so slender that if it were pressed continuously againstthe mold forming material in the flask during compacting of the moldforming material the mandrel would bend inwardly so that the mold formedthereby would be of undesirably reduced diameter at the center. It isfound that the mandrel does not strike the mold forming material at thesame points at each revolution of the flask so that a uniformcylindrical compacted mold rather than a fluted mold is formed.

After the mold forming material has been thus acted upon by the mandreland the mold has been completely formed within the flask the flask ismoved back to its original position coaxial with the mandrel whereuponthe mandrel'is withdrawn toward the right viewing Figure 3 to itsinoperative position/as shown in that figure.

The cycle of operations is the same when double hub pipe is being formedexcept that when the mandrel is introduced into the flask to consolidateand smooth the mold forming material therein to form the mold the hubbut may be otherwise variously embodied within the scope of thefollowing claims.

I claim:

1. Molding apparatus comprising a rotary'hollow flask, means forrotating the flask, a freely rotatable undriven slender flexible mandreladapted to be disposed within the flask and to rotate therein as theflask rotates tocompact mold forming material against the inside of theflask and means for relatively adjusting at will the distance beween theaxis of the flask and the axis o'f'the mandrel, the mandrel having aneccentric portion which strikes "the mold forming material withsuccessive blows as the mandrel and flask rotate and the mandrel movesrelatively to the flask away from the axis of the flask, such strikingof the eccentric portion of the mandrel against the mold formingmaterial compacting the mold forming material against the inside of theflask and rotating the mandrel, the mandrel intermediate blows againstthe mold forming material being substantially relieved of bendingstress, whereby a mold of small diameter may be formed using a slenderflexible mandrel with the mold being substantially free of distortionwhich would result from bending of the mandrel.

2. Molding apparatus comprising a rotary hollow flask having anenlargement at an end thereof, means for rotating the flask, a freelyrotatably undriven slender flexible mandrel adapted to be disposedwithin the flask and to rotatetherein as the flask rotates to compactmold formr. it)

ing material against the inside of the flask, the mandrel having anenlargement at an end thereof generally radially aligned with theenlargement in the flask, the enlargement in the mandrel'being' coaxialwith the axis of rotation of the mandrel, and means for relativelyadjusting at will the di'stance'between the axis of the flask and theaxis of the-mandrel, the mandrel having an eccentric portion which'strikes the mold forming material with successive blows as-the mandreland flask rotate and the mandrel moves relatively to the flask away fromthe axis of the-flask, such striking of the eccentric portion of themandrel against the mold forming material compacting the mold formingmaterial against the inside of the flask and rotating the mandrel,themandrel intermediate blows against the moldforming material beingsubstantially relieved of bending stress, whereby a mold of smalldiameter may be formed using a'slender flexible mandrel with the moldbeing substantially free of distortion which would result frombending ofthe mandrel.

3. Molding apparatus comprising a rotary hollow flask havingenlargements at the ends thereof, means for rotating the flask,-a freelyrotatably undriven slender flexible mandrel adapted'to be disposedwithin the flask and to'rotate therein as the flask rotates to compactmold forming material against the inside of the flask, the mandrelhaving enlargements at the ends thereof respectively generally radiallyaligned with the enlargements in the flask, the enlargements in themandrel being coaxial with the axis of rotation of themandrel, and meansfor relatively adjusting at will the distance between the axis of theflask and the axis ofthe mandrel, the mandrel having an eccentricportion intermediate the enlargements which strikes the moldforming-material with successive blows as the mandrel and flask rotateand the mandrel moves relatively to the flask away from the axis of theflask, such striking of the eccentric portion of the mandrel against themold forming material compacting the mold forming material against theinside of the flask and rotating the mandrel, the mandrelintermediate-blows against the mold forming material being substantiallyrelieved of bending stress, whereby a mold of small diameter may beformed using a slender flexible mandrel with the mold beingsubstantially free of distortion which would result from bending'of themandrel.

References Cited in the file of this patent UNITED STATES PATENTS804,329 Martin Nov. 14, 1905 853,633 Gurry May 14, 1907 2,076,790 MyersApr. 13, 1937 2,138,623 Campbell Nov. 29, 1938 2,340,262 Crawford Jan.25, 1944 2,499,387 Johnston Mar. 7, 1950 2,631,342- Romine Mar. 17, 19532,729,865 Kaveny Jan. 10, 1956

